Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K19/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic element specially adapted for rectifying, amplifying, oscillating or switching, covered by group H10K10/00
  • H10K19/10—Integrated devices, or assemblies of multiple devices, comprising at least one organic element specially adapted for rectifying, amplifying, oscillating or switching, covered by group H10K10/00 comprising field-effect transistors
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
  • H10K10/40—Organic transistors
  • H10K10/46—Field-effect transistors, e.g. organic thin-film transistors [OTFT]
  • H10K10/462—Insulated gate field-effect transistors [IGFETs]

Definitions

• the invention relates to logic components made of organic field effect transistors, in which the switching speed is increased by replacing the resistors.
• Logical gates such as N ⁇ ND, NOR or inverters are the elementary components of an integrated digital electronic circuit.
• the switching speed of the integrated circuit depends on the speed of the logic gates and not on the speed of the individual transistors.
• these gates are implemented by using both n- and p-type transistors and are therefore very fast. This cannot be achieved with organic circuits because there are no sufficiently stable n-semiconductors. For organic circuits, this means that a conventional resistor is used instead of the n-type transistor.
• the object of the invention is therefore to create a logic gate with organic field-effect transistors, in which the missing * classic "n-type transistors are replaced by other than classic resistors.
• the invention relates to a logic gate comprising at least a first and a second organic field effect transistor (OFET), the first OFET being a p-type OFET and the second OFET in the logic gate can be used as a resistor.
• OFET organic field effect transistor
• the first OFET has an extremely thin semiconductor layer or a negative threshold voltage.
• the logic gate includes a first and a second OFET with an extremely thin semiconductor layer or a negative threshold voltage.
• the second OFET without gate voltage has off currents which are only approximately one order of magnitude below the on currents, so that the second OFET can be switched off further by applying a positive gate voltage.
• the logic gate comprises at least 4 OFETs (cf. FIG. 6).
• the logic gate has 2 data lines (input and output), these data lines being at different potentials.
• the * OFET which can be used as a resistor in the gate *, is either an OFET with an extremely thin organic semiconductor layer (approx. 5 to 30 nm) or an OFET with the conductivity of the organic semiconductor layer through targeted treatment (for example hydrazine treatment and / or targeted oxidation) has been reduced to such an extent that the off-currents are only approximately one order of magnitude below the on-currents.
• the “OFF current is the current that flows when there is no potential at the gate electrode against the source electrode and the “ON current * (for p OFETS) is the current that flows when a negative potential is applied to the source electrode.
• a component with a linear current-voltage characteristic is referred to here as a "classic resistor”.
• the on-characteristic 1 and the off-characteristic 2 are shown in a current-voltage diagram. These characteristics correspond to the switched on and the switched off state.
• the intersections 3 and 4 of the curves with the resistance line 5 correspond to the switching points of the inverter.
• the output voltage swing 6 of the inverter is very large, which means that the inverter can be switched on and off easily.
• the charge-reversal currents 7 and 8 are different. This means that the inverter can be switched to * High "quickly, but slowly to * Low".
• FIG. 2 also shows the prior art, the second case, in which the charge-reversal currents 9 and 10 are of the same size, but the voltage swing 11 is too small. The corresponding inverter cannot be switched off completely.
• Figure 3 finally shows a current-voltage curve of a logic gate according to the invention:
• the current-voltage diagram of a logic gate as shown in FIG. 3 comprises at least one OFET with an extremely thin semiconductor layer as a replacement for a conventional resistor.
• OFETs with extremely thin semiconductor layers have from 5 to 30 nm, preferably from 7 to 25 nm and particularly preferably from 10 to 20 nm a special output characteristic field, which is shown schematically in Figure 3.
• the voltage swing 12 is large enough so that the inverter can also be switched off completely and the recharge currents 13 and 14 are of the same size, as a result of which the inverter can switch over quickly.
• Another advantage is the amount of charge reversal current, which is very high with this type of transistor. Due to the thin semiconductor layers, the transistors pass from the rising edge 15 very steeply into the saturation region 16. This behavior of the output characteristic can be used in conventional p-Mos technology to build logic circuits that have high charging voltages. As a result, the switching speed of the components is high.
• the content of the invention is to use this effect for the production of fast logic gates. These gates are fast and can also be switched off easily, despite conventional p-Mos technology.
• the replacement of the classic resistor can alternatively also be carried out by special treatment of the semiconductor layer of an OFET and a special circuit layout for the logic components.
• Typical OFETs have very low off currents without gate voltage. By treating the organic semiconductor in a targeted manner, it can be achieved that the off-currents are reduced only by approximately are an order of magnitude below the on-currents (for example by hydrazine treatment or by targeted oxidation). These special OFETs can then be switched off further by applying a positive gate voltage. This gives you an OFET, which can be switched on by a negative gate voltage and switched off by a positive gate voltage (like an n-type transistor). This effect is also used according to the invention (in addition to the above-mentioned effect of the extremely thin semiconductor layers) in order to produce fast logic components.
• the basic element of these logic components is a series connection of at least two OFETs with different dimensions of the current channel, in such a way that without a gate voltage, the current channel of one OFET is significantly more conductive than that of the other. The consequence of this is that the supply voltage across the two current channels only drops at the less conductive current channel.
• the switching process takes place by applying a negative gate voltage to the OFET with the poorly conductive current channel and at the same time applying a positive gate voltage to the OFET with the more conductive current channel.
• Figure 5 shows the current-voltage diagram of such a logic gate. Both characteristics are shifted by the special circuit layout or by the special circuit layout in combination with a treatment of the semiconductor layer, which results in a high voltage swing and at the same time high charge-reversal currents.
• An inverter consists of two of these basic elements, i.e. at least four transistors. When the inverter is switched, two transistors are switched on and the other two are switched off at the same time.
• FIG. 6 The circuit of an inverter is shown in FIG. 6 and the circuit of a ring oscillator is shown in FIG.
• 2 x 2 transistors are required, because a positive voltage is required to switch off one transistor and at the same time a negative voltage to switch on the other.
• 2 of the above-mentioned basic elements are now combined, one providing a positive voltage at the output and the other a negative one.
• An inverter with this new circuit technology thus has 2 inputs and outputs, with 0V or +/- V applied to each of these outputs.
• FIG. 6 shows the inverter embodiment: the interconnection is an important point here.
• point 1 is the supply voltage, which is +/- V here.
• Point 4. is the earth.
• the points marked with 3 symbolize the inputs and the points marked with 2 represent the outputs of the inverter.
• the logical "low” is reached when there is no voltage at outputs 2.
• Logically V ⁇ high “means that +/- V is present at output 2 of the inverter, that is to say that the data line comprises 2 lines which are at different potentials.
• CMOS inverter In contrast to the inverter described above, which comprises at least 4 OFETs, a conventional CMOS inverter, for example, consists of 2 transistors. At 0V on the input, transistor 1 is conductive and the other 2 is non-conductive (thus the supply voltage at 2 drops). If the voltage is negative, 1 becomes non-conductive and the other 2 becomes conductive (thus the supply voltage is at 1).
• Figure 7 shows a ring oscillator. For this circuit, an odd number of inverters are interconnected by placing the output on the input of the next inverter. The last inverter is then also connected to the first inverter, creating a ring. The purpose of a ring oscillator is to circulate the signal in the ring by constantly switching the following inverter.
• FIG. 4 shows some exemplary embodiments of the logic components that comprise OFETs with the extremely thin semiconductor layers:
• the circuit symbol 21 symbolizes a p-conducting OFET.
• An inverter 22 can be an interconnection of a transistor with a resistor.
• a signal applied to the input (* High “or 'Low") is reversed (inverted) and is then applied to the output (as * Low “or ⁇ High”).
• An embodiment of the logic gate is e.g. a flip-flop, which could also be constructed from these OFETs.
• the logic gates are advantageously produced by spraying, coating, knife coating, printing or other manufacturing processes which can be operated as a continuous process.

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• Logic Circuits (AREA)
• Metal-Oxide And Bipolar Metal-Oxide Semiconductor Integrated Circuits (AREA)

Priority Applications (3)

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Publications (2)

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Cited By (5)

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• 2002
  • 2002-03-21 DE DE10212640A patent/DE10212640B4/de not_active Expired - Fee Related
• 2003
  • 2003-03-14 WO PCT/DE2003/000843 patent/WO2003081671A2/de not_active Ceased
  • 2003-03-14 US US10/508,640 patent/US7223995B2/en not_active Expired - Fee Related
  • 2003-03-14 CN CNB03810086XA patent/CN100361389C/zh not_active Expired - Fee Related
  • 2003-03-14 JP JP2003579280A patent/JP4171703B2/ja not_active Expired - Fee Related
  • 2003-03-14 EP EP03720186A patent/EP1502301A2/de not_active Withdrawn

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